Fever stops and rash begins is diagnostic of-

Ans. is 'b' i.e., Roseala infantum Roseola infantum (Sixth disease or exanthem subitum) It is caused by human herpes virus-6 (HSV-6) Similar illness is caused by Parvovirus B-19 and Echovirus. o Age group involved is 6 mt to 3 yr. o Incubation period --> 5 to 15 days. Clinical manifestations Abrupt onset with high grade fever, mild pharyngitis and Coryza. The temprature conies down rapidly in 3 to 4 days when a macular or maculopapular rash appear, staing from trunk and sometimes extending to the extremities and face. Rash lasts for 24 hours, and disappear in 1-2 days without pigmentation or desequamation. o There is occipital and post-auricular lymphadenopathy.